Module 2 : Theory of Earth Pressure and Bearing Capacity
Lecture 6 : Introduction [ Section 6.1 Different Theories of Earth Pressure ]
1.
Lateral Earth Pressure For At Rest Condition
The earth retained behind retaining walls may be natural earth or filled up soil. These backfill materials exert certain lateral pressures on the wall. If the wall is rigid and does not move with the pressure exerted on the wall, the soil behind the wall will be in a state of elastic equilibrium .
Fig.2.3 Development of active and passive earth pressures
To reach the plastic state, for to develop we need a minimum displacement . If the displacement developed is less than , the pressure developed is called partially mobilized earth pressure which is more than .
Similarly for passive case the wall moves towards the soil and the soil tries to resist the movement of the wall. To reach the passive case a very high movement is required, .
to develop we need a minimum displacement 
. If the displacement developed is less than 
, the pressure developed is called partially mobilized earth pressure which is more than 
. 
. 
